Method of preparing oxidized



Patented Nov. 22, 1949 METHOD OF PREPARING OXIDIZED I DRYING OIL IzadorJ. Novak', Trumbull, Conn, assignor to Raybestos-Manhattan, Inc.,Passaic, N. J., a corporation of New Jersey N Drawing. Application April30, 1947,

Serial No. 745,107

This invention relates to a method of reduc-' ing the color formed in anair-blown or oxidized unsaturated vegetable oil when it is subsequentlyheated to cause it to react, polymerize or harden, and to the product ofthis method.

It is well known that when pro-oxidized or blown vegetable drying orsemi-drying oils are heated above the temperature at which they wereoxidized for the purpose of increasing theirbody 0r viscosity, or inmaking a varnish, the color of the oil deepens markedly. In most casesthe darkening is far beyond the color permissible in a varnish or paintvehicle, except for colors 'suchas maroon, green .or black, wherethe'color of the vehicle is not an important factor. This darkening onheating has therefore largely precluded the use of blown oils in makingvarnishes where heating is necessary to combine or dissolve resins withthe oil. In making a vehicle for a light colored paint, the color of theoriginal blown oil is usually very light, but blown oils without furtherheat treatment have poor aging qualities when used for this purpose. Onthe other hand, if the blown oil is heated to 500-600 F., its agingqualities are greatly improved, but the color has been darkened beyondthe desirable range.

While the method described hereinafter has usefulness in blown dryingoils generally, I have found that it is particularly efiective in theblown oils described in my U. S. Patent No. 2,178,604 wherein theoxidation is carried out at a temperature below the usual range of blownoil manufacturing temperatures. Low temperature oxidation, say below 200F., results mainly in the addition of oxygen to double bonds and toactive hydrogens in the fatty acid chains together with a considerableshift of non-conjugated double bonds to conjugated double bonds. I havefound that there is a minor amount of splitting of the chains resultingin the formation of short chain oxidized and unoxidized acids, such aspyruvic, glycollic, capric acids, etc. Oxidation at higher temperatures,such as to about 250 F., also probably results in higher breakdown ofthe oxidized long chains and distillation or breakdown of the acidsformed thereby. Present in all vegetable oils are the natural coloringmaterials: chlorophylls, xanthophylls, carotenes, etc. These coloringmaterials also probably are susceptible to oxidation of the same type asthe fatty acid chains and to the subsequent breakdown with heat.

One characteristic of the oxidized products above mentioned is a greateror less degree of water solubility. The shorter oxidized chains are 6Claims. (o1. 260-406) water-soluble, the longer oxidized chains appearto be hydrophilic. v

My invention comprises the water extraction'of the water-soluble(including hydrophilic) materials present in an oxidized drying oil, toproduce a new oil free from these Water-soluble or extractablesubstances. I

When this new oil is bodied by heating it evolves much less gas onheating to higher temperatures, up to say 575-600 F., and results in abodied oil having a color distinctly lighter than that of the same oilhandled in the same manner and carried to the same body but not waterextracted. I am aware that water extraction has been widely used toremove dirt, dust, mucilage and the like from raw oils, to remove alkaliand soap from alkali-treated oils, or excess acid from acid-treatedoils, but it should be notedthat these operations are confined torefining of substantially unoxidized oils. The herein'described methodof removing color forming bodies from a highly oxidized light coloredoil before bodying so as to obtain the advantage of their absence whenthe oil is bodied, is new to the best of my knowledge. The results areunexpected in that there is no reason to support that thewater-extractable portions of a blown oil include substances which arepotential color formers when heated, since the water extract ispractically colorless.

The vacuum dehydration of the water extract gives an amber coloredresidue which is not -ade-' quate to produce the diiference incolor'shown by the new extracted oil. The residue darkens onheating inair. However, when the water" extract is remixed with the extracted oiland'the water carefully evaporated from the oil, and the oil is bodiedas ordinarily done, the final color is of the same order as that ofunextracted oil.

In this connection, water extraction of the refined oil before oxidationhas no appreciable effect towards color reduction of the oxidized and 3On separation, the water layer showed a pH of 2.6 indicating a strongorganic acid content. The loss in weight of the oil was 0.25%,representing water-solubles in the oil. The water- 4 From the foregoingexamples it is observed that the water extraction of the blown oilsmentloned which are characteristic of the classes of drying andsemi-drying vegetable oils leaves solubles reduce Fehling solution,indicating alde- 5 oil residues which behave diflerently on heat hydicand/onketonic substances.

The oilllayenafter water extractionwas; heated cautiously at first up to300 F., to eliminate its water content. It became clear at 275-300 F. Oncontinuing the heating to 575 F., the

bodying temperature, it darkened "less and frothed less than theunextracted oil of the same derivation. It bodied at thewsamezrate..as--.,the unextracted oil, and reached a Z96 body in approximately onehour at 575 F. The color of the unextracted oil was about 15, n, theGardner- Holdt scale after bodying in airtoZ-6. ;The color of the waterextracted bodied oil was"1'2% after similar treatment. With vacuumrbody-ing.

under a C02 atmosphereg'the color of unextracted oil was; .111, I {thatofthe; extracted aoil .-.1l. ,fIThe bodying time under vacuumwas-rconsiderably longer-:about 715/2 =hoursto; Z16.

. Sinceethe wwater extract ,:is acid zit "would .be

expfictedzthatthe acid number ,of ltheextractedgoods-explanation.torsthisgphenomenon. .--It,may

be vtha the waterextr ction removes .a fat-- splitting agent whichresults: in the lower acid content-noted. Whatevertheicausefithe 210Wacid number -.-bodied oil ;is-,a -i ery desirable productbodyingathan-athe. unextractedoils in that final color. is: generallyreduced and certain. oils show marked reduction in acid content in thebodied sstate.

These improvements were not predictable on -the basis of the prior artsince washing unoxidized oils subsequent to standard refining methodsashcwseno comparableeffects.

;:I claimas. myzinyentionz ElJThe method =..:of inhibiting darkening of.-vegetable drying. Oil which has been oxidized by .::,treatmentwith anoxygen-containing gas at a "temperature below 250 F. on subsequentheatingsabove said temperature, which comprises water extracting saidoxidized oil prior to said iurther heatin g,,thereof.

.,2.;.The,.proc.ess-. of ,treating unsaturated vegetablel'dryingioil,,\whi'ch comprises. blowing it .with an. oxy en-containing gas. at..a.. temp.erature..below 250 F. and extractingit withwater.

3. Ilka-process ,ofitreating unsaturated vegetable drying.,.oil, whichcomprises treating ,the oil. withranoxygen-containing gas. at a temperaiiurer below .250.. F... extracting it with "water to remove.potentialcolor forming .materials. thereirom and recovering a treated.oiLcharacterized by reduction .in ,,acid number a and reduction .incolor darkening. =and. ..frothing on, ,he atin g. rabove 250 -E.,.,ascompa1ted.to alike derived, oxidized andheatedoilin the absenceofsaidinterrnediate watenextraction treatmentstep.

.Ah-The -process of. claim: 3 wherein the oil ,is oxidized atatemperaturebelowjw? F.

. 5. \The pmcess .of; .claim. 3 whereinithe. oxidized sincefoilsv withhighacidnumbers; are Jess :water-.-. .40 and-Mater extractedoil "is.bodied. by,. heating. to

resistant and-yreactymoreawith pismentsnandgdry 110. 18, slowly-than;those.gwithrloweraacidz numbers; It ;is .=welll-rknown that -lowTH-Cid'gbOdiGdOilS command hisherr emiums in. th i r n z oil markets thahi hfacidbodied oils.

ow;:temperatur 10W;n refined =-sQyaean-.oi1 handled ii irlthe sa-me;manner as the l-aboves example vand:rina viurn bodi dl'to the rea m deree sav aacolor; Oil .15. versus.;;18-= f -thercomparame unextractedsoya bean oil.

:Asain, irefin d;;1ins d;Loi1-:-b1o\un Ito. J. visco ity at i1240 ,F.;accordi1 1g:to standard goil blowing practicedos/distinguished from Iow-temperature blow n ,r-afte 'wesh seanchb d in gave a'idisatemperaturebetween 500and600iF.

.6. .The process oi. claim. 3 whereinrthe oxidized and water.extracted-"oil heatedat ,a varnish cooking temperature to .desiredvarnish oil viscosity.

HIZADORJJ. NOVAK.

REFERENCES ,.CITED ;-The j followingi-references-:areof record: in-thefile of this:.patent:

"UNITED? STATES PATENTS Number t n lvrlis t r c lc r than th r nwashe-ioilswheni bodied.

